Passive flutter suppression with rotary nonlinear energy sink

Abstract The control of aeroelastic phenomena, such as flutter, is of great interest due to its high amplitude self-excited characteristic. Nonlinear Energy Sinks (NES) are vibration absorbers whose nonlinear coupling to the structure contributes to broad excitation ranges for passive suppression. This paper investigates the attachment of a rotary-type NES (RNES) to an aeroelastic typical section to suppress nonlinear flutter oscillations passively. An unsteady aerodynamic loads model is used based on the Theodorsen and Wagner approaches. Pitching structural nonlinearity is added, inducing limit cycle oscillations in the airfoil. The system is modeled and numerically simulated. A dynamic characterization is done, obtaining the mechanisms of action of RNES through a regime identification, and its typical bifurcation behavior is accessed. A parametric analysis based on the system bifurcation over different RNES configurations is used to understand how each design parameter influences vibration mitigation performance and how absorption regimes correlate with RNES effectiveness. An energy analysis is carried through to conceive the activation of the Targeted Energy Transfer suppression mechanism and an energy-based parametric analysis of RNES performance. The results indicate that NES efficiency for flutter postponement is related mainly to low-radius devices located near the leading edge. RNES mass and angular damping parameters also present an impact but are limited due to subcritical behavior.